To see a list of Cisco IOS releases that support Cisco Unified SRST, see the Cisco Unifed CME Compatibility Matrix. Cisco Unified SRST is compatible with the same Cisco IOS releases as Cisco Unified CME.

** These phones are supported on IOS release 15.1(1)T with SRST 8.0, not on 15.0(1)XA release.

Supported Platforms and Memory Specifications: SCCP/SIP IP Phones*

Cisco Platform

Maximum Total IP Phones**

Maximum SCCP/SIP IP Phones

Maximum Total Ephone-dns or
Virtual
Ports

Recommended DRAM

Recommended Flash Memory

Cisco 880 SRST ****

4

4

50

512

128

Cisco 1861

15

15

48

256

128

Cisco 2801

not supported

not supported

not supported

not supported

not supported

Cisco 2811

not supported

not supported

not supported

not supported

not supported

Cisco 2821

not supported

not supported

not supported

not supported

not supported

Cisco 2851

not supported

not supported

not supported

not supported

not supported

Cisco 2901

35

35

200

512

256

Cisco 2911

50

50

300

512

256

Cisco 2921

100

100

400

512

256

Cisco 2951

250

250

500

512

256

Cisco 3825

not supported

not supported

not supported

not supported

not supported

Cisco 3845

not supported

not supported

not supported

not supported

not supported

Cisco 3925

730

730

1000

1024

256

Cisco 3925E

1350

1350

2000

1024

256

Cisco 3945

1200

1200

1800

1024

256

Cisco 3945E

1500

1500

2500

1024

256

Catalyst 6500 CMM***

not supported

not supported

not supported

not supported

not supported

* Memory recommendations and maximum numbers of IP phones are for common Cisco SRST configurations only. Systems with large numbers of phones and complex configurations may not work on all platforms and can require additional memory or a higher performance platform.

** The Maximum Total IP Phones can be split between SCCP and SIP phones as long as the maximum total of IP phones are reached.